345 - Physiology Flashcards
What is the source of cholecystokinin?
I cells (duodenum, jejunum)
What are the actions of cholecystokinin?
↑ pancreatic secretion
↑ gallbladder contraction
↓ gastric emptying
↑ sphincter of Oddi relaxation
How is cholecystokinin regulated?
↑ by fatty acids and amino acids
Through which pathway does CCK cause pancreatic secretion?
muscarinic pathways
What is the source of gastrin?
G cells (antrum of stomach)
What are the actions of gastrin?
↑ gastric H+ secretion
↑ growth of gastric mucosa
↑ gastric motility
how is gastrin regulated?
↑ by stomach distention/alkalinization, amino acids, peptides, vagal stimulation
↓ by stomach pH < 1.5
In what syndrome is gastrin classically elevated?
Zollinger-Ellison syndrome
What is the effect of chronic PPI use on gastrin?
↑
What is the effect of phenylalanine and tryptophan on gastrin?
potent stimulation
What is the source of glucose-dependent insulinotropic peptide?
K cells (duodenum, jejunum)
What are the actions of glucose-dependent insulinotropic peptide?
Exocrine: ↓ gastric H+ secretion
Endocrine: ↑ insulin release
How is glucose-dependent insulinotropic peptide regulated?
↑ by fatty acids, amino acids, oral glucose
What is another name for glucose-dependent insulinotropic peptide?
gastric inhibitory peptide (GIP)
Secretion of what hormone accounts for the more rapid utilization of glucose upon eating vs. IV delivery?
GIP
What is the source of motilin?
small intestine
What is the action of motilin?
produces migrating motor complexes (MMCs)
How is motilin regulated?
↑ in fasting state
What kind of drugs are used to stimulate intestinal peristalsis?
motilin receptor agonists such as erythromycin
What is the source of secretin?
S cells (duodenum)
What are the actions of secretin?
↑ pancreatic HCO3- secretion
↓ gastric acid secretion
↑ bile secretion
What regulates secretin?
↑ by acid, FAs in lumen of duodenum
What is the relationship between HCO3- and pancreatic enzymes?
↑ HCO3- neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function
What is the source of somatostatin?
D cells (pancreatic islets, GI mucosa)
What are the actions of somatostatin?
↓ gastric acid and pepsinogen secretion
↓ pancreatic and small intestine fluid secretion
↓ gallbladder contraction
↓ insulin and glucagon release
How is somatostatin regulated?
↑ by acid
↓ by vagal stimulation
What is the overall effect of somatostatin?
It’s an inhibitory hormone with antigrowth hormone effects (inhibits digestion and absorption of substances needed for growth)
What are the actions of nitric oxide?
↑ smooth muscle relaxation, including lower esophageal sphincter
What substance imbalance is implicated in the ↑ LES tone of achalasia?
Loss of NO secretion
What is the source of VIP?
Parasympathetic ganglia in sphincters, gallbladder, small intestines
What are the actions of VIP?
↑ intestinal water and electrolyte secretion
↑ relaxation of intestinal smooth muscle and sphincters
How is VIP regulated?
↑ by distention and vagal stimulation
↓ by adrenergic input
What is a common tumor that secretes VIP?
VIPoma: a non-α, non-β islet cell pancreatic tumor
What are the symptoms of VIPoma?
Watery Diarrhea (copious)
Hypokalemia
Achlorhydria
(aka WDHA syndrome)
